Switch with lift-off ramp

ABSTRACT

The invention describes a switch, preferably a steering column switch, provided with an actuating member moved across the contact sections rigidly connected to the housing in a substantially pushing way. It is the object of the invention to provide a steering column switch which, being of a small-sized design, permanently provides for good contact making between the contacts to be interconnected. This problem, in the practice of the invention, is solved by ramps raising the contact bridge in the transitory area. Advantageous embodiments refer to the design of the ramp of the conductor bank and of the contact bridge.

TECHNICAL FIELD

The present invention is concerned with a switch for automotivevehicles, in particular, steering column switches.

BACKGROUND OF THE INVENTION

Switches of the afore-mentioned type, on the one hand, should be able toswitch substantial load currents so as to pass energy to lamps andengines. On the other hand, switches of the afore-described typeincreasingly serve for indirectly actuating power consuming units thenactuated directly through electronic circuits. Advantageously, steeringcolumn switches of this type should, therefore, also be able to switchweak control currents.

In order to be able to neatly switch also weak flows of this type, thetransition resistance of the switches is to be kept low. Specialprovision is, therefore, to be made to prevent pollution of thecommunicating contact faces by corrosion, scaling, arc formation oradhering residual insulating material.

In conventional switches, contact sections rigidly arranged on thehousing in abutting relationship within the contact plane areelectrically interconnected or separated by a pushing motion of contactbridges. The disadvantage involved with switches of this type resides inthat the two contact sections are separated by insulating material thatwill get into close contact with the contact bridge when sweeping aboutit. The displaced contact bridge will thereby entrain remainders ofinsulating material or of the plastic casing in which are embedded thecontact sections. Once the contact bridge runs up another contactsection, the insulating material, in part, is transferred to the contactbank of the said contact section or is burnt into the contact faces bythe arc, if formed, thereby polluting the contact face. By sizing theswitch adequately large, the bearing force of the contacts can so bedimensioned that during the counter-directed pushing motion the contactsare again rubbed clean. However, large-dimensioned switch sizes are notjustifiable for weak currents.

It is the object of the invention to provide a small-sized switch, thecontact faces of which are substantially kept free from pollution so asto enable use thereof as a switch for large and weak currents. Hence,the invention resides in that the contact bridge is raised at anappropriate point before leaving a contact section to be then lowered atan appropriate point of a new contact section.

Accordingly, the pushing motion, at the important re-switching points,is combined with a lifting motion. The resultant advantage resides inthat the actual contact face is not placed in contact with theinsulating material surrounding the contact sections. Moreover, contactmaking, due to the lifting motion, is abruptly changed rather thanlinearly by a dragging movement through passage from one contact sectionto the next. Hence, three defined conditions of the contact bridge areattained in respect of which the transitory times are relatively short,to wit: contact making of the contact bridge in one contact sectiononly; contact making of the bridge to one bridge portion only with theother bridge portion lifted off; and, finally, rapid transition to thecondition connecting the two contact portions respectively to anothercontact section. Also, it is of importance to the invention that one ofthe contact portions, during lifting, does not yet form an arc becausethe other contact portion is still in close electrical contact with thecontact section.

A particularly simple design suitable for lifting off a contact portionis disclosed according to which a ramp is provided over which a contactportion of the contact bridge moving along a contact section is raisedin a direction vertical to the plane of the contacts and lowered overthe next contact section. Hence the motion of the contact portionfollows the oblique sloping ramp faces.

To reliably prevent areas of the contact bridge dragging along thestationary contact sections from getting into contact with thesurrounding insulating material, in particular, with the insulatingmaterial of the ramp, at least one ramp is provided which is arrangedlaterally of the contact faces of contact bridge and contact section sothat the area of the contact bridge running on the ramp will not getinto contact with the contact face on the contact sections.

To that extent, a particularly simple design is set out wherein theramps are symmetrically arranged within the interval so that the forcesexerted by the two ramps on the contacts are also symmetrical, therebykeeping the contact bridge well in trace with the contact sections. Toreliably separate the portions of the contact bridge in communicationwith the ramp or insulting material, if any, from the portions servingto establish contact with the contact sections, the contact zonespreviously referred to as contact portions are formed on the contactbridge that get into electrical contact with the ramps but not with thecontact sections. Moreover, contact zones are formed that exclusivelyget into contact with the contact sections to establish a reliableelectrical contact.

To improve contact making between contact bridge and contact section, apreferred embodiment is disclosed for conducting weak currents as due tothe dragging motion of contacting faces that, conversely, never get intocontact with plastic material and are easily separated with no major arcformation, the contact faces can be kept substantially clean. Usually,no special coating is required.

For further reducing the contact face to facilitate cleaning of thecontacts, contacts can be constructed having a pointed bearing face forthe contacts. If in several bridges moving in parallel on contactsections, different currents are to be conducted it may, be advisable toprovide some of the bridges, in the direction of the contact sections,with grooves laterally embracing the contact banks, thereby selectivelyproviding a larger contact face. However, if exclusively controlcurrents are to be switched, it is adequate for the bridge not to befurnished with grooves and to reduce the bearing face of the contactbridge on the contact bank accordingly.

To improve contact making of the contact bridge, the contact bridge isresiliently guided in an actuating member in a direction vertical to thecontacting plane. Due to the flexible abutment of the contact bridge onthe contact banks, a safe bearing pressure even in the event ofirregularities of the contact bank is ensured. Moreover, an elevatedspring pressure can be used for mutually keeping clean the contactfaces.

The present invention provides for a reliable guidance of the contactbridge within the actuating lever so that the bridging contact, towardthe contact banks, always remains in alignment with the contactsections, preventing deflection from the direction of extension of thecontact banks.

Another advantage resides in that the distance covered by the contactbridge toward the contact bank is limited involving special advantagesfor the assembly of the actuating lever within which the movable contactbridge is safely and rigidly held.

In a preferred embodiment, stops are used as projections on lugs forengaging associated guiding slots within the actuating member. Byenabling the contact bridges to engage the actuating lever, easyassembly, movable guidance over the actuating lever and safe arrangementthereover to prevent loss thereof is obtained.

The present invention is suitable for use with slide switches in whichthe bridging contact performs a straight-forward movement. However, theinvention is also suitable for use with contact sections and contactbanks, respectively, which are arranged in series at an angle, whereinthe contact banks themselves also can be of a curved configuration. Itis particularly advantageous for the contact banks to beunidirectionally curved on the contact sections and to be arranged withthe same radius of curvature in series. A design of this type isparticularly suitable for steering column switches in which theactuating lever performs a swivel movement about a fulcrum resulting ina circular sector-type movement of the bridging contact.

A simple design for the contact banks is disclosed wherein the contactbank can be formed from the contact sections by stamping so that acontact section of that type can also be punched from a simple contactplate.

Another simplification is disclosed in that molded to the contactsections stamped from contact plate are plug connections.Advantageously, the contact sections can be formed from a punching grid.In order to enable the individual contact banks to be more easily placedand held in an injection mold, they are, in addition, connected, duringthe injection process, to electrically conducting, mechanicallyconnecting bridges that, after the injection operation, are severed bypunching, irrespective of whether or not the said severing webs arecoated by extrusion with plastic material.

In order to further reduce the bearing face of the contact bridge, thetwo contact sections serving both for guiding the contact bridge throughthe ramps and for contact making, in the direction of extension of thecontact banks, are spatially separated from one another and areelectrically interconnected. The contact areas also can be punched froma single contact plate and can be formed by subsequent deformation, withthe two contact areas, advantageously, being electrically interconnectedby a web. Suitably, a centering projection can be molded into the saidmechanically rigid web with the said centering projection forming apoint of attack for the preloading spring. As the contact areas haveboth a mechanical control function over the associated ramp and acontact-making function over the contact section rigidly connected tothe casing, in a preferred embodiment, the contact area includes acurved surface thereby safeguarding that the contact bridge is preventedfrom interlocking with the ramp. In addition, the slope of the ramp isto be comparatively flat, normally not to exceed 2/10 mm, therebypreventing, in particular, switch noises from occurring and extendingthe operating life of the switch.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematically shown three-dimensional view of a cut from aswitch housing with injection-molded contact banks and a contact bridgeseated thereon.

FIG. 2 is a sectional view of the arrangement of FIG. 1 shown laterallyof the contact bank.

FIG. 3 is a scaled-down plan view of an intermediate bottom of a switchhousing with a plurality of injection-molded parallel contact sections.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, FIG. 1 shows the bottom face 1 of a switchaccording to the invention into which are cast the contact sections 2,3.The two contact sections are electrically separated at the level of dualramp 5, it being possible for the ramp to be injection-molded along withthe molding of the bottom face 1 so as to be formed integrally with thebottom face of the same material. Contact banks 4 are molded from thecontact section 2,3 by stamping, with a contact bridge 6 with the twocontact areas 7 and 8 thereof being seated on the contact bank 4 of thecontact section 2.

Each of the two contact areas 7,8 comprises contact zones 9,10 and 11,respectively, with the contact zones 9,10 running up the ramp 5, whilethe contact zone 11 exclusively serves for making contact with theassociated contact bank 4 of the contact section 2. The two contactareas 7,8 are interconnected by a bridging member 12 configured as a webthat includes a centering projection 13 fixing the point of attack of aspring 14. The spring is supported with the end being the free end inFIG. 1 on an actuating lever of a steering column switch (not shown)simultaneously engaged by two lugs 15,16 serving for guiding the contactbridge 6 in the actuating lever.

Projections 17 on lugs 15,16 engage guiding grooves of guiding slotswithin the actuating lever (not shown), thereby insuring that thecontact bridge 6 is immovably or rigidly held with respect to theactuating lever in that the path of movement of the lugs is limited bystops struck by projections 17. DE-OS 42 26 508 discloses substantialelements of the design of the contact bridge 6 so that there is no needfor them to be described herein.

The contact banks 4 comprise a curvature 18 whereas the contact areas7,8 are respectively provided with a curved surface 19,20. The zones9,10 during movement of the contact bridge 6, will run, in the directionof extension of the contact banks 4, up the two ramps 21,22 of the dualramp 5, thereby lifting the contact zone 11 from the appertainingcontact bank 4. If the contact bridge 6 is continued to be moved in thesame direction, the contact zones 9,10 are lowered again; contact zone11 will then be seated on the contact bank 4 of the contact section 3.As shown in FIG. 1, the contact banks 4 of the contact sections 2,3 canbe formed by being punched from the punch grid.

FIG. 2 is a side view of the contact bridge 6 seated on the contact bank4 of the contact section 2. The section is arranged slightly laterallyof the contact bank so that only a ramp web 23 interconnecting the twopartial ramps 21,22 is shown. FIG. 2, through a dashed line, indicatesgrooves 24 laterally embracing the upper marginal area of the contactbank 4, thereby not only permitting a centered guidance of the contactbridge 6 on the contact bank 4 but also, if need be, an enlarged contactface. FIGS. 1 and 2 additionally disclose that the appertaining contactsections 2,3, in the longitudinal direction thereof, are in alignmentwith one another; however, they can also be arranged in staggeredrelationship if the contact bridge 6 is configured accordingly.

FIG. 3 additionally shows that curved contact banks 4 can be provided,with plug connections (not shown in the drawing) being molded toappertaining contact sections. However, it can be clearly seen that thecontact sections are punched from a contact plate and that,subsequently, connecting webs are severed by punching passage holesthere into. This will result in a substantially more complexconfiguration of the contact sections than shown in FIGS. 1 and 2.

We claim:
 1. A switch, comprising:at least one contact bridgedisplaceable in a contact plane, said contact bridge including a firstand a second contact areas interconnected by a bridging member, saidcontact bridge being pushable from a separating position to a connectingposition and being resiliently guided in a direction vertical to saidcontact plane by an actuating member arranged within an actuating leverof a steering column switch, the resilient guidance of said contactbridge being provided by a spring acting upon said bridging member, twocontact sections including contact banks elevated in a rail-type mannerthat are electrically separated from each other by an interval and to beinterconnected by said first and second contact areas of said contactbridge, said contact sections being rigidly fastened to a switchhousing, said first and second contact areas of said contact bridgebeing arranged in a longitudinal direction of said contact banks in aspaced relationship from one another, at least one ramp arrangedlaterally of said interval between said contact sections, said firstcontact area of said contact bridge being provided with at least oneramp zone guided through said at least one ramp, and with at least onecontact zone sliding on said contact banks, wherein said contact bridgechanges from contacting one of said two contact sections to contactingboth of said contact sections during a pushed transition from saidseparating position to said connecting position, and wherein during saidtransition said first contact area of said contact bridge is lifted bysaid at least one ramp over said contact plane from the contact sectionpreviously contacted to be lowered thereafter down to the other contactsection to be newly contacted.
 2. A switch according to claim 1, furtherincluding two ramps on both sides of the interval.
 3. A switch accordingto claim 1, wherein the contact banks facing the contact areas arecurved such that a small face of contact is formed between the contactbanks and the contact areas of the contact bridge.
 4. A switch accordingto claim 1, wherein the contact bridge comprises two lugs substantiallyextending in the preloading direction of the spring preloading thecontact bridge, with the lugs serving for guidance within the actuatingmember, and two stops are provided confining the path of the contactbridge toward the contact bank.
 5. A switch according to claim 4,wherein the stops constitute projections on the lugs engaging associatedguiding slots within the actuating member.
 6. A switch according toclaim 4, wherein the contact banks extending in the contact plane areunidirectionally curved.
 7. A switch according to claim 4, wherein thecontact banks to be interconnected are in substantial alignment with oneanother.
 8. A switch according to claim 4, wherein the contact banks arepunched from the contact sections.
 9. A switch according to claim 1,wherein the contact sections are conductor lines punched from sheetmetal, with the conductor lines integrally passing to electrical plugconnectors.
 10. A switch according to claim 1, wherein the contactsections form parts of a sheet metal punch grid embedded in an extrudedcoating of plastic material, with the conductor lines being severed onlyafter extrusion.
 11. A switch according to claim 1, wherein the bridgingmember is provided with a centering projection centering the point ofattack of the spring acting upon the bridging member.
 12. A switchaccording to claim 1, wherein the contact area has a curved surface socurved as to serve as a run-on slope with respect to the ramp.
 13. Aswitch according to claim 1, wherein the contact area is so curved that,in connection with the curvature of the contact bank, it forms areduced, self-cleaning contact face.
 14. A switch according to claim 1,wherein the contact zones of the contact bridge are provided withgrooves through the side faces of which the contact zones are laterallyguided on the contact banks.